Various types of enzymes may be included in oral formulations to act as therapeutic agents. For example, enzymes may be included to hydrolyze oral polysaccharides or to inhibit bacterial growth. More specifically, for example, it was reported that enzymes such as mutanase, dextranase, papain, and 1,3-glucanase can be employed in oral formulations for removing plaque deposits.
Generally, enzymes by nature are vulnerable to changes of environment such as pH, temperature, and ion concentration, and thus it is usually necessary to take measures to protect enzymes to maintain intended oral-care efficacy of the enzymes. To improve performance of enzymes, enzyme-stabilizing agents, such as chelating agents and anti-oxidizing agents, have been suggested. Examples of such enzyme-stabilizing agents are EDTA, sodium gluconate, sodium bisulfite, metal gallates, sodium stannate, and ascorbic acid.
Among the enzyme-stabilizing agents, however, bisulfite materials, i.e., compounds containing bisulfite ion, are shown to be toxic to some individuals, and/or often alter the organoleptic properties of an oral care formulation. Therefore, it may be desirable to remove or reduce bisulfite materials in enzyme compositions before the compositions are further processed and delivered to consumers. Even though bisulfite materials can be removed through conventional techniques such as base extraction and neutralization by an oxidizing agent, these techniques often adversely affect the catalytic activity of enzymes in oral compositions. Thus, it is desirable to introduce an alternative method for removing bisulfite materials which does not negatively affect activity of enzymes in a composition to be treated. To date, there has been no convenient method to remove bisulfite materials from enzyme compositions, which method can be conducted under neutral, non-oxidizing conditions.